State health officials have raised Middleboro’s EEE risk level to “high” after detecting the virus in a mosquito sample collected in the town.

So far this year, Massachusetts has had no human cases of eastern equine encephalitis, which can be transmitted through the bite of an infected mosquito.

The insects that recently tested positive in Middleboro were of a mosquito species that feeds on the blood of mammals. The mosquito samples were collected July 25, and the state announced the results Wednesday night.

The state Department of Public Health announced it is increasing ground spraying in Middleboro and surrounding communities. As a result of the positive test, the risk level in the towns of Halifax, Plympton and Wareham has been raised from “low” to “moderate.”

Public health officials recommend limiting exposure to mosquitoes by using insect repellant, removing standing water and limiting outdoor activities during evening and nighttime hours.

The state conducted aerial insecticide spraying in 21 southeastern Massachusetts communities between July 20 and 22. Health officials reported the spraying killed 60 percent of the mosquito population in targeted areas.